sharon sanders
Editor-in-Chief & President
Eurosurveillance, Volume 21, Issue 18, 05 May 2016
Rapid communication
EXPERIMENTAL STUDIES OF SUSCEPTIBILITY OF ITALIAN AEDES ALBOPICTUS TO ZIKA VIRUS
M Di Luca [SUP]1[/SUP] [SUP]2[/SUP] , F Severini [SUP]1[/SUP] [SUP]2[/SUP] , L Toma [SUP]1[/SUP] , D Boccolini [SUP]1[/SUP] , R Romi [SUP]1[/SUP] , ME Remoli [SUP]3[/SUP] , M Sabbatucci [SUP]4[/SUP] , C Rizzo [SUP]5[/SUP] , G Venturi[SUP]3[/SUP] , G Rezza [SUP]3[/SUP] , C Fortuna [SUP]3[/SUP]
snip
[h=2]Discussion[/h] Little is known on ZIKV despite its significant epidemic potential [12]. The introduction and dissemination of this previously neglected flavivirus in Latin America, raised concern in temperate climate countries with established Ae. albopictus populations [3]. In light of the spread of this mosquito species in Italy, proven vector in the 2007 outbreak of CHIK [5], it is particularly important to evaluate its vector competence for ZIKV and to assess the potential risk transmission in Italy as well as in other Mediterranean countries. Our study shows that the Italian Ae. albopictuspopulation is susceptible to ZIKV, allowing viral replication and dissemination also in the salivary glands. The short persistence of the virus in the mosquito?s saliva, the PTR value of 3% and the long EIP indicate a low transmission efficiency compared with that of Ae. aegypti. In addition, it should be noted that despite the use of a long-established mosquito colony, not representative of a wild population, the vector competence of Ae. aegypti for ZIKV was significant in our experiment. A recent modelling study [13] that was based on parameters of susceptibility to infection of the Ae. albopictus derived from mosquito populations from the United States and Singapore [4,14], also estimated a low risk of sustained autochthonous transmission of ZIKV in northern Italy. Our results are similar to the above results on AmericanAe. albopictus and substantially confirm the low epidemic potential of ZIKV in Italy. However, the epidemic potential and the capacity to cause long chains of transmission depends on a series of factors such as the abundance of the mosquito population, the density of the human population, feeding host preferences, biting rates and environmental conditions. High mosquito density, day-biting activity, opportunistic feeding behaviour and climatic and environmental adaptability can affect the efficiency of Ae. albopictus as a vector, favouring its primary role in epidemics, also in the presence of a limited vector competence [15].
Our results also have important public health implications for preparedness. In fact, the extended EIP, which is consistent with the results of studies using American Ae. albopictus mosquitoes [4], would allow the implementation of mosquito control measures that are likely to be more efficient than those implemented in areas infested by the tropical mosquitoAe. aegypti. Moreover, our analysis of offspring of both species from the first and second gonotrophic cycle showed no evidence of transovarial transmission of ZIKV; this finding adds knowledge on the bionomics of this vector and may aid the optimisation of vector control management. Finally, ZIKV appears to be less well adapted to the Italian Ae. albopictusthan the A226V variant of CHIKV (data not shown), which caused more than 250 cases in Italy after a single introduction from Kerala, India [5,16].
In conclusion, this experimentally infected Italian Ae. albopictus population appeared to be a competent vector for ZIKV, albeit less efficient than the primary vector Ae. aegypti. However, we should not forget the risk posed by CHIKV and dengue virus that remains high in southern European countries, where small outbreaks and clusters of autochthonous cases have been already documented [17,18].
http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=22468
Rapid communication
EXPERIMENTAL STUDIES OF SUSCEPTIBILITY OF ITALIAN AEDES ALBOPICTUS TO ZIKA VIRUS
M Di Luca [SUP]1[/SUP] [SUP]2[/SUP] , F Severini [SUP]1[/SUP] [SUP]2[/SUP] , L Toma [SUP]1[/SUP] , D Boccolini [SUP]1[/SUP] , R Romi [SUP]1[/SUP] , ME Remoli [SUP]3[/SUP] , M Sabbatucci [SUP]4[/SUP] , C Rizzo [SUP]5[/SUP] , G Venturi[SUP]3[/SUP] , G Rezza [SUP]3[/SUP] , C Fortuna [SUP]3[/SUP]
snip
[h=2]Discussion[/h] Little is known on ZIKV despite its significant epidemic potential [12]. The introduction and dissemination of this previously neglected flavivirus in Latin America, raised concern in temperate climate countries with established Ae. albopictus populations [3]. In light of the spread of this mosquito species in Italy, proven vector in the 2007 outbreak of CHIK [5], it is particularly important to evaluate its vector competence for ZIKV and to assess the potential risk transmission in Italy as well as in other Mediterranean countries. Our study shows that the Italian Ae. albopictuspopulation is susceptible to ZIKV, allowing viral replication and dissemination also in the salivary glands. The short persistence of the virus in the mosquito?s saliva, the PTR value of 3% and the long EIP indicate a low transmission efficiency compared with that of Ae. aegypti. In addition, it should be noted that despite the use of a long-established mosquito colony, not representative of a wild population, the vector competence of Ae. aegypti for ZIKV was significant in our experiment. A recent modelling study [13] that was based on parameters of susceptibility to infection of the Ae. albopictus derived from mosquito populations from the United States and Singapore [4,14], also estimated a low risk of sustained autochthonous transmission of ZIKV in northern Italy. Our results are similar to the above results on AmericanAe. albopictus and substantially confirm the low epidemic potential of ZIKV in Italy. However, the epidemic potential and the capacity to cause long chains of transmission depends on a series of factors such as the abundance of the mosquito population, the density of the human population, feeding host preferences, biting rates and environmental conditions. High mosquito density, day-biting activity, opportunistic feeding behaviour and climatic and environmental adaptability can affect the efficiency of Ae. albopictus as a vector, favouring its primary role in epidemics, also in the presence of a limited vector competence [15].
Our results also have important public health implications for preparedness. In fact, the extended EIP, which is consistent with the results of studies using American Ae. albopictus mosquitoes [4], would allow the implementation of mosquito control measures that are likely to be more efficient than those implemented in areas infested by the tropical mosquitoAe. aegypti. Moreover, our analysis of offspring of both species from the first and second gonotrophic cycle showed no evidence of transovarial transmission of ZIKV; this finding adds knowledge on the bionomics of this vector and may aid the optimisation of vector control management. Finally, ZIKV appears to be less well adapted to the Italian Ae. albopictusthan the A226V variant of CHIKV (data not shown), which caused more than 250 cases in Italy after a single introduction from Kerala, India [5,16].
In conclusion, this experimentally infected Italian Ae. albopictus population appeared to be a competent vector for ZIKV, albeit less efficient than the primary vector Ae. aegypti. However, we should not forget the risk posed by CHIKV and dengue virus that remains high in southern European countries, where small outbreaks and clusters of autochthonous cases have been already documented [17,18].
http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=22468